


Mass Calculations

by nautilicious



Category: Sherlock (TV), Sherlock Holmes & Related Fandoms
Genre: Alternate Universe, Alternate Universe - Space, Demisexual Sherlock, First Kiss, First Time, Friends Protect People, Johnlock Roulette, M/M, Post-Reichenbach, Sherlock Gets It Wrong, the cold equations
Language: English
Status: Completed
Published: 2013-12-20
Updated: 2013-12-20
Packaged: 2018-01-05 07:31:20
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 6,954
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1091240
Author URL: https://archiveofourown.org/users/nautilicious/pseuds/nautilicious
Summary: <blockquote class="userstuff">
              <p>An unspecified number of years into a sci-fi future, Sherlock jumps from Barts. John picks up the pieces, and then Sherlock comes back. </p><p>Post-Reichenbach. In Space.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> Thanks to [hedgehogandotter](http://hedgehogandotter.tumblr.com/) for finding all of the things in the story that I’d hoped no-one would notice, and [midnoz](http://midnoz.tumblr.com) for asking the hard questions. Both of these wonderful betas improved my work considerably. Undoubtedly this story would be even better if I hadn’t ignored some of their suggestions in favor of posting before S3 airs.

Captain John Watson checked the readout, verifying that his Emergency Drop Ship had ejected safely from the cruiser. His tiny ship flew, light and quick, towards the developing situation on the Wayford colony. He opened a comm channel.

“ _Starfire,_ I’m on my way _,”_ he said. 

“Safe flight, Captain Watson,” came the reply. “Good luck with that virus.”

“Thanks, Lt. Morstan,” he said. “Hope it won’t come down to luck.”

“We’d love to pick you up after your drop, but it’ll be _Blue River_ on that run. Maybe we’ll see you next time.” John smiled, hearing the unspoken offer in Mary’s voice. She was still interested, then. He’d passed a number of evenings losing money at poker with the Ops team — Mary especially; he couldn’t seem to win against her. He found himself, not for the first time, wishing he’d accepted the invitation to that strip poker game. He liked Mary; she made him laugh. He hoped she knew that.

“Maybe next time,” he said. “Safe flight, _Starfire,”_ he said. He closed the channel.

John turned towards an auxiliary terminal and pulled up the latest data on Wayford. A third of the colony’s population had fallen ill before they sent the mayday, he read, so half the population might be infected before he arrived. This situation occurred with distressing frequency out on the frontier: colonists, exploring ever further into space, continually encountered new ways to die. Expeditions focused on terraforming and survival rarely had the advanced medical facilities needed to synthesize vaccines. 

In this case, the specifics of the virus matched one that had swept through the colony on New Tejas, so a vaccine existed that could be delivered via drop ship. He hoped that the virus didn’t mutate; he wasn’t a pathologist. Well, maybe he’d only have to do the job he was sent to do: administer the vaccine, deal with the plague patients, and sort out the quarantine. Then he’d be on general medical duty until _Blue River_ came by to collect him in six months. He really hoped the job wouldn’t require any emergency biochemistry.

He thought of Sherlock leaned over a microscope at Bart’s and a quick cascade of memories flashed through his mind, ending, as always with the flare of a black coat against the sky and Sherlock bleeding out on the pavement. John felt the familiar pang in his chest. He usually tried not to think about Sherlock. However, he had nothing to do in the next six hours but wait for landfall. He rubbed his fingers between his eyes. 

The ghost of depression lingered, despite John spending the last two years holding it at bay. He’d left London, refreshed his medical skills, and learned to pilot a drop ship, all to avoid the emptiness Sherlock left behind. Without Sherlock —  the fizz and fireworks, the thrill and terror — it all seemed like so much work. The colony worlds held all the excitement of a combat zone with a smaller percentage of its dangers, and no-one asked him about his feelings.

The hair on the back of his neck prickled and John heard a whisper of sound behind him. There should be no unexpected sounds; he should be alone. He stood, turned, then froze. A tall, familiar form stood in front of the cargo cupboard, incongruous, impossible, in the tiny cabin of the ship _._

John stared. His eyes darted to check the oxygen read-out. The levels read as normal, so he wasn’t hallucinating due to a lack of air. Sherlock shifted his weight and John heard the rustle of his long black coat sliding past his legs.

“John,” Sherlock said.

John’s body moved forward without thought, his hand shaking as he reached forward to touch the lapel of Sherlock’s coat. John could smell the warm, wooly scent of it. He had forgotten that smell, reminded again in this moment unfolding in truth rather than imagination. Sherlock, the man and not the memory, lived.

The shakiness in John’s hand spread through his body and for a moment he feared his leg would give out. Instinctively he flexed his thigh muscles for balance. He kept his feet but he couldn’t stop the trembling in his belly. Sherlock’s gaze held his, waiting. John thought he knew all of Sherlock’s expressions but he had never seen anything like the mix of shifting emotions in Sherlock’s eyes. Or perhaps Sherlock only mirrored the uncertainty John felt displayed on his own face.

 _Sherlock was alive._ Joy flashed through him, pure and quick, and then the questions began to race through his mind. Sherlock watched him closely, as though he could see John’s thoughts as they formed. Sherlock’s expression shifted, and John recognized it: Sherlock had braced himself for John’s anger. He’d had seen it tensing John’s muscles before John himself had realized it.

Rage swept over him as the magnitude of the lie reverberated in his head. John’s fist clenched to rise and strike, to pound his suffering into Sherlock’s flesh: the nights of grief, the tears, the descent into quiet misery. The silence. The longing. He’d begged Sherlock’s grave for this miracle but now that he had it he wanted to smash Sherlock back into dust.

A sharp bolt of pain arrowed through the center of John’s chest. The room undulated, his vision wavering. He felt a muffled ringing in his ears. He closed his eyes, exhaled. His rage passed almost as quickly as it had risen, unsustainable in the face of his sheer relief at seeing his friend again. John’s fists loosened and his head drifted forward to rest on Sherlock’s shoulder. Sherlock inhaled sharply, slowly curling his arm around John’s ribs.

John’s breathing slowed, the shakiness easing from his limbs. He raised his head and the intensity of Sherlock’s grey-green gaze startled him. Only a step separated them yet it suddenly seemed a vast distance. Sherlock’s expression remained unfathomable, but it held a kind of fire that John thought he recognized. John glanced at Sherlock’s mouth, wondering, his own mouth suddenly dry. 

 The grating siren of an alarm filled the air. John startled, moved to stand before the computer display. A red light shone where a red light should not. The mass indicator displayed an impossible number. “Oh my God,” John said. 

“What is it?” Sherlock asked.

The ship’s mass registered over the limit; of course it did: the fuel engineers had not calculated for the weight of Sherlock’s body. When decelerating at the colony the extra mass would burn unanticipated grams of fuel, increasing every second. The fuel tank would empty too soon and the ship would burn up in the atmosphere well before landing. 

“You can’t be here. We’re burning too much fuel. We’ll— the colonists—” John ran his hands through his hair, clasped his head. “What in God’s name were you thinking?”

Sherlock’s mouth opened to reply but John didn’t let him speak. “How did you not know what a terrible idea this was? They even made a daytime drama about what happens to people who stow away on a drop ship.”

Sherlock shrugged, and John could tell he was attempting nonchalance. “Deleted, I imagine. Especially if they made a movie about it. But John—“

“Sherlock, there were signs with large red letters. Very serious signs.”

“I usually ignore signs like that. Corporations like to protect their liability; signs rarely mean real danger, only danger for idiots.” Sherlock frowned and John suspected they’d had the same thought about idiots. Then Sherlock shook his head as though re-settling his feathers, and despite himself John felt a half-smile quirk his lips.

“In any case,” Sherlock said, “There’s bound to be a logical solution to the fuel problem. Everything has fail-safes these days.”

John’s smile vanished. He felt a slow wave of queasiness begin in his stomach. He knew the regulations. He’d seen the crap made-for-telly movie. Worse, he knew the maths. He didn’t have a choice.

“No, Sherlock. Not this time.” He swallowed. “The equations are logical. Immutable. Not even you can win an argument with physics.”

John opened a comm channel. _“Starfire,_ this is Captain Watson. I need the Commander.”

“You ok, Captain?” Mary asked.

“I’ve got an emergency. I need the Commander, now.” Mary didn’t waste any more time; another voice came on within the minute.

“This is Commander Allen. Situation report?”

 “I’m on course,” John said, “about six hours out from the colony—“

“Is the medicine stable?”

“It’s not the medicine.” He took a breath. “I’ve got a stowaway.”

John heard the Commander huff down the line. “I know stowaways are rare these days, Captain, but the regulations are perfectly clear. Your telemetry is good but it won’t stay that way. I recommend jettisoning within the hour.”

“I don’t think you understand, Commander. My stowaway is Sherlock Holmes.”

“I don’t care who it is. The lives of an entire colony depend on that medicine.”

“His brother is Mycroft Holmes. I can’t speak to how much your life will be worth if you don’t get me a better answer. Call Mycroft. And get someone to look at the numbers. There’s got to be something you can do.” John closed the connection.

Sherlock’s face paled. John flashed back to how Sherlock’s skin had looked nearly translucent against the pavement outside of Bart’s. John closed his eyes, took a slow breath. 

“Jettison,” Sherlock said. “Jettison the extra weight. Me.”

“Every gram is calculated,” John said. “More fuel means less medicine. There’s a bit of a safety margin, of course. But not enough for this.”

“And we can’t orbit and wait for a rescue ship, I assume.” Sherlock said.

John forced himself to meet Sherlock’s eyes. “This _is_ the rescue ship. No one else is coming. I won’t even get a lift off the planet until the next cruiser comes through in six months.” 

“Six months?” Sherlock asked.

John shrugged a shoulder. “It costs a lot to fly a cruiser way out here. Costs even more to land and take off again, so they throw the nearest drop ship at a colony on their way past and pick it up later.” 

The comm chimed. Sherlock stood as still as a stone.

“Captain Watson, this is Commander Allen. We’ve run your situation through the computers. We’ve figured you a shallower orbit — you’ll do a couple of skips across the atmosphere and pick up some extra delta-vee that way. We’ve also changed your landing site. You’ll splash down in the southern ocean and we’ll send helicopters.”

“And the mass calculation?”

The line went silent for a second. “Still twenty-five kilos over,” came the answer. “But we’ve bought you some time — you don’t have to jettison until thirty minutes before splashdown. There might be time for him to get a comm through to his brother.”

John swallowed. “That’s it, then?”

“That’s the best we can do for you, Captain.” The Commander paused. “I’m sorry. _Starfire_ out.”

He heard the regret in the Commander’s voice as clearly as he heard the reminder to duty. Five and a half hours for Sherlock to live. 

John opened his mouth, not sure what he intended to say, when Sherlock spun around, taking quick inventory of the few items in the cabin: the Pilot’s couch, the cargo cupboard of medicine where Sherlock had stowed away, and the supply locker which held water and a few personal items for John.

“Surely you don’t need this couch,” Sherlock said. His pointing finger seemed to accuse the couch of wastefulness.

“It houses most of the piloting controls, so yes, I do need it. Plus the damned thing is bolted to the floor. But I can cut away some of it,” John said. “We’ll be mostly on autopilot with the updated course, and I can handle a landing without seat belts, considering.” He cocked his head, imagining where he’d make his cuts. “Could maybe get us two kilos.”

Sherlock steepled his hands together and pressed them to his lips. John couldn’t hide the catch in his breath at seeing that familiar pose. Sherlock glanced at him and quirked a brow. “Shall I throw myself down upon the couch?” he asked. 

John smiled. “If it would help,” he replied. Sherlock smiled back. The mixture of fondness and adrenaline in his expression filled John with equal parts affection and terror.

“We can lose a third of our oxygen before risking hypoxia,” Sherlock said.

John thought about it. “A quarter would be better. I’ll have to cycle it through the airlock, and that’s going to take some time.” He stepped over to the console and tapped out a few commands. Sherlock came to stand behind him. After looking over John’s shoulder a moment Sherlock reached around him and began typing.

“What—“ 

“This is one circumstance in which your two-fingered typing might literally cost us our lives. Which command cycles the airlock?”

John huffed a bit, but answered. Sherlock resumed typing, his cheek brushing against John’s temple. John resisted the urge to lean into the warm, firm line of Sherlock against his back. _Alive,_ he thought, _he’s alive._ Sherlock typed a bit, then paused. John selected the required sub-menu without being asked. Then Sherlock’s fingers flew, quickly and efficiently automating a process which would dump a frightening amount of their air into space. 

Sherlock’s hands left the keyboard but he did not step away. John closed his eyes. He didn’t know whether Sherlock was checking over his work or lingering against John’s shoulders, and he didn’t care. Sherlock’s ridiculous disregard for physical space had annoyed him plenty of times in the past, but now he reveled in it. He wanted Sherlock to absently brush against him, to stand too close, to prove in each moment his unquestionable aliveness. The airlock clicked through its first cycle and John opened his eyes.

“That ought to get us about three kilos, though we won’t know for about four and a quarter hours,” said Sherlock. 

“Along those lines,” John said, “we can toss the water. And the doors to the supply locker, if my laserknife can get through the hinges. Couple of kilos there.”

“Our clothes should net us at least four kilos,” Sherlock said. 

“Yes, I had thought of that, actually,” John said. “Your coat probably weighs 2 kilos by itself.” John couldn’t help grinning. “Guess I should have worn more interesting pants.” 

“You’ll risk the mass?” Sherlock asked.

“My pants probably weigh about 30 grams. I’ll chuck them if we need to, but I’m going to dismantle the only item of furniture in here and the floor is cold.” John pursed his lips. “Let me do the cutting and then we can strip down.”

John emptied the supply locker and retrieved the laserknife. “Toss those things, would you?” he asked, tilting his head towards the small pile on the floor. He placed the blade against the hinge of the locker and watched it slowly melt through the metal. Sherlock put all but one of the water containers in the airlock. Then he picked up John’s tiny satchel and rummaged through it. John felt his face heat. He kept his eyes on his work.

Sherlock withdrew the small, homemade pouch from the satchel. “That was my favorite scarf,” he said, running one long finger over the fabric. He poured out the contents: the cap to a test tube, a bullet, the end of a violin string. A quick smile ghosted across his lips. John shrugged. “Didn’t figure you’d be using it.”

Sherlock’s smile vanished. “John—“

John shook his head. “Do you really want to have this conversation while I have a laserknife in my hands? I need to focus.” He couldn’t read Sherlock’s expression out of the corner of his eye, didn’t want to look at him. “It was just sentiment. You know, for those of us who feel it.”

Sherlock moved towards him, his hand sliding down John’s arm to lightly grasp his wrist. John had already turned off the laserknife. Sherlock’s fingers rested cool and steady on John’s skin. 

“I’m sorry,” Sherlock said. John took a breath, turned his head. He knew what Sherlock pretending to apologize looked like. This wasn’t it. Sherlock’s face was open and without artifice, radiating sincerity that John believed unfeigned.

“Damnit, Sherlock, we were partners. You don’t leave your partner behind. Why did you do it?”

Sherlock made a sharp exhale through his nose, compressing his lips. John suspected that the Don’t Be an Idiot, John look would be next, possibly paired with the You See But You Don’t Observe speech. “No,” John said, twisting his wrist out of Sherlock’s grasp. “You don’t get to make that face. I spent _two years_ mourning you. I didn’t even cry over my sister’s grave, Sherlock. I mourned her, but I didn’t miss her every day the way I missed you.”

Sherlock swallowed, remained silent. 

“I just kept thinking that I could have done something different, done something to make it not happen. That if I’d been quicker or more observant you wouldn’t have been able to trick me, that I could have stopped you.” John felt the grief, accepted but never mastered, constricting his throat. 

“They needed to think that I was dead so that I could hunt them down,” Sherlock said. And then, softer, “I was trying to protect you.”

 John felt the anger like a slow pressure on his spine, his back muscles engaging and tensing as he spoke. He preferred it to the grief. “I was a soldier, Sherlock. I know how to kill, and I’m a better shot than you. I didn’t need protecting.”

“You couldn’t defend against a sniper,” Sherlock said.

“What?” John asked.

“Moriarty had a sniper on you. If I hadn’t jumped he’d have killed you.”

John felt cold. “You jumped from a building to keep me from getting shot.”

“Well, made it seem as though I jumped, yes,” Sherlock said. “You shot a man for me once, so it seemed fair. And,” he looked away a moment, “you would have done the same for me.”

“I would have _actually_ died for you," John said. “I would have faked my death for you, too. But. _I would have told you_. I would never — whatever you were off doing, fucking alone and without help, Sherlock! We should have done it together. How could you think—“ He pinched the bridge of his nose, took a breath. “Give me a minute.”

John closed his eyes, rubbed his thumb across his forehead, kept breathing. “I can’t do this right now. I really just need to deal with the problem at hand.”

“I don’t want to die knowing you’re angry with me,” Sherlock said.

John winced. “You won’t. Not if we can find enough mass to jettison.” He gestured to the melted metal of the supply locker. “So let me work.”

“John.” Sherlock looked serious and hesitant at the same time. “We have time. I see how much it hurt you. I won’t take the chance of dying without your forgiveness.”

The last two years unwound behind John’s eyes: thinking he saw Sherlock in doorways and cafes; yearning for it to be a magic trick; the pitying glances; the gun in his mouth on a stormy night. Sherlock’s lie had nearly destroyed him. Without the lifeline of the drop ship training, the slow reassembly of self…the weight of it pressed into his chest. It felt like too much to forgive. And yet, if they didn’t get the mass calculations right Sherlock would die in five hours. Really die, no miracles possible, and it would be John’s hand on the lever. The thought brought an acid wash of bile to the back of his throat.

“God, why couldn’t we have had this conversation—Wait.” John’s shoulders tightened. “You were on the _Starfire_. This whole week. Why didn’t you talk to me then?“ 

Sherlock glanced away, fiddled with his pocket. “I didn’t want you to be able to walk away.”

John wished he could deny that he would have, that he could have responded with anything but incredulous joy, except that obviously he _hadn’t._ He imagined Sherlock knocking on the door to John’s quarters on the _Starfire_. He suspected that he would have punched him and then closed the door in his face. Might not have ever forgiven him. A long moment passed.

“Look,” John said finally. “I understand that you think it was necessary to leave me behind. I think I’m going to be mad about that for a while. I can’t just forget it. But. I’m glad you are alive. And that you did it to save me means a lot. I— forgive you.”

Sherlock’s shoulders shifted, relaxed. “Thank you,” he said.

John nodded. “Let’s get back to it. We’re wasting time.”


	2. Chapter 2

In the end, they were 15 kilos short.

“No,” Sherlock said. “Absolutely not. You aren’t a regeneration candidate, John.”

John shrugged. “You aren’t either,” he replied. He felt clammy, fear roiling in his stomach. “I’ve always had a dodgy leg,” he said. “I’m used to it. Hell, a cyber-leg will probably work better. Should have done that in the first place.”

“Amputation seems a bit severe for a psychosomatic limp,” Sherlock said. 

“It’s decided,” John said.

“No, it isn’t,” said Sherlock. “The colony needs a doctor; how can you help them if you’re in recovery?”

“Cyber-limbs graft on quickly. It’s the physical therapy that takes ages. I can do everything I need to do in a hoverchair until I can get back on my feet. Fucked-up but functional; sort of my speciality.”

Sherlock ran his hands through his hair, tugged. “There has to be something I’ve missed, something else we can do.”

John shook his head. “There isn’t, believe me. We’ve done everything we can.” John rubbed the back of his neck. “It’s not just us, you know. It’s everyone on the colony, too. 278 people, Sherlock. Children. My leg isn’t worth their lives.”

Sherlock grimaced. “It’s my mistake that got us here.” He gripped John’s arm. “You can’t do this. You can’t do this for me.” 

John smiled bleakly. “I can,” he said, “and I will.”

“But why? My leg is heavier than yours; it’s safest to take mine. You’re not being logical.”

“Shut up!” John yelled. “There is no logic in this! Do you think I want to do it? I hated those days, with the cane. But I can go back to it, because you know what I can’t do again? See you die. Two years mourning, and here you are, whole. Perfect. How can you possibly think that I could take a blade to you, saw through your flesh and bone? Mutilate you. I can’t. Not even to save you.” 

He reached out to grip Sherlock’s wrist. The pulse beneath his fingers fluttered like a hummingbird. “Please, Sherlock. I can’t live with myself otherwise.”

Their eyes locked. Sherlock’s eyes glistened. John caught his breath, felt his own eyes grow moist. Sherlock's hands came up, pressed themselves lightly to John’s cheeks and cradled his face.

“John,” he said, “you are the truest friend that anyone could have. I don’t deserve you.”

John laughed shakily. “You’re right about that.” 

John had spent most of his adult life in the company of other men. He understood the closeness engendered by intense circumstances: the men of his units had endured hardships and bled on each other, suffered in loss and exulted in triumph together. Their connection seemed beyond the body, except in the ways it was completely about the body and its frailty, its protection and defense. John thought of it as brotherly love, forged in adversity, unspoken but obvious.

This did not feel like that. The air between their bodies felt scorching. 

Sherlock bent his head until their lips were inches apart and did not drop his gaze. John couldn’t look away. “John,” Sherlock whispered, his voice a low rumble, “there is something else I want to do before I die.”

“Not going to let you die,” John whispered back, and then Sherlock closed the gap.

Sherlock’s lips pressed his softly, carefully. They remained that way for a moment, mouths moving slowly, and then John grabbed the collar of Sherlocks’ coat and pulled. Their bodies pressed together and Sherlock made a soft noise in the back of his throat. John slid his tongue against Sherlock’s lips and then inside, deepening the kiss. He’d never kissed a man before but that didn’t seem to matter: his blood heated the same, and Sherlock’s mouth tasted so good. Right now they were both alive and _whole_ , and afterwards he would be so, so broken. He didn’t care. Nothing seemed more important than licking into Sherlock’s mouth and drawing — yes, _that_ noise from his friend.

Suddenly Sherlock’s hands slid across the front of John’s trousers, squeezing his cock through the fabric in a way that made John groan against Sherlock’s mouth. Sherlock pulled away long enough to say, “Let me, let me do this for you—“ and then they were kissing again.

John caught his breath. “No,” he said, panting a bit. “Wait. Not _for_ me. Not out of pity. Is this because—“ John didn’t want to remind them what he would have to do very soon now, but Sherlock had no such inhibition.

“No, it’s not because you’re about to cripple yourself for me,” Sherlock said. His hand moved to John’s hip and he gripped it firmly, preventing John from pulling away.

“You know, I really did think that you were asexual,” John said. Sherlock grazed John’s earlobe with his teeth and John made a noise somewhere between a laugh and a moan. “Guess I had that one wrong.”

Sherlock's voice rumbled low in John’s ear and John shivered. “Only with people that I—“ He broke off, burying his face against John’s neck. John felt him inhale deeply. “I don’t want to do this.”

John knew he didn’t mean the sex. He put his arms around Sherlock, reached up to stroke his fingers through his curls. “I know,” he said. “It’ll be all right.”

The computer beeped. John released Sherlock and went to check the display. “That’s the last of the air cycled,” he said. Sherlock’s face looked pinched with tension and sadness both. John wanted to erase that look.

“Time to get naked,” John said. “Seems a much better idea now than it did earlier.”

Sherlock began removing his coat but John put out his hand to stop him. 

“Let me,” he said.

He circled behind Sherlock and slid the sleeves of his coat down his arms, then spread the coat gently on the floor. He returned to Sherlock and slipped his first shirt button undone. He’d seen the skin beneath countless times but never knew he’d want to press a kiss to it, just like that, his lips against Sherlock’s throat and Sherlock’s pulse racing beneath his mouth. John realized that he wanted to unveil Sherlock inch by inch, to savor every scent and sight, but time moved against them. He paused. Sherlock’s hands came to cover his own.

“Next time,” Sherlock said, and then undid the rest of his buttons efficiently. 

John stripped off his clothes while Sherlock finished undressing. No sense in keeping the pants now. He placed all of their garments except the coat into the airlock and cycled it. He turned.

“Christ,” John breathed out. “Look at you.” Sherlock’s skin managed to look rich and silken even under the industrial glow of the ship’s lights. The shock of dark hair at his groin drew John’s gaze, and he saw that Sherlock’s cock was thick and uncut, glistening at the tip. It pulsed slowly with Sherlock’s heartbeat. John swallowed. His own cock throbbed at the sight. _Alive, alive,_ his blood sang. _Alive and well._ He wanted to crawl inside Sherlock’s body, imprint himself into Sherlock’s very cells, so that Sherlock would carry within him the memory of John’s body unmarred and whole. He wanted to bring Sherlock’s great intellect home into its flesh, to draw Sherlock down into the raw, disorganized messiness of the physical and see him gasping and coming undone under John’s hands. He wanted to press inside Sherlock’s body, or maybe be pressed into, to dissolve into each other until the space between them vanished and they could no longer tell where one ended and the other began. Suddenly he wanted everything and didn’t know where to begin.

“You know I’ve never—“ John said, “and there’s no time and no lube and I—“

Sherlock stepped forward, brushed his hands down John arms and took his hands. “Come here,” he said. “Your body knows.” Sherlock drew him down to his coat and then spread out his long body on top of it. He tugged John closer. John ran his fingers across the planes of Sherlock’s chest, his stomach, and then brought his body down on top of Sherlock’s. John gasped as his cock slid against Sherlock’s hip. He instinctively shifted his weight and then they were pressed together, rubbing up against each other. Sherlock made a low, breathy noise and bucked his hips into John’s.

Sherlock raised his hand to John’s mouth expectantly. John kissed it, and then Sherlock pressed it against John’s lips again. John licked it slowly and Sherlock’s eyes darkened. Desire pulsed through John's body. Sherlock reached down and wrapped his hand around both of them, stroking them together, and John heard the noise torn from his throat echoed by Sherlock.

The ship hurtled them through the black night of space, their mouths clinging, tongue dancing against tongue. John set his teeth into Sherlock’s bottom lip and pressed until Sherlock whimpered, their cocks thrusting against each other as though their lives depended on it. 

“God, that’s—“ John groaned. “Don’t stop.” John pressed kisses to Sherlock’s neck clumsily, his entire existence focused on the feel of Sherlock’s steady hand, the slide of Sherlock’s body against his own. His breath rasped in his throat, every nerve in his body alight with pleasure, and then his orgasm rolled over him in a wave. He felt his come slicking between Sherlock’s fingers and Sherlock groaned. John panted, his open mouth warm against where Sherlock’s neck met his shoulder. He felt Sherlock’s body tense beneath him. John bit down, and Sherlock cried out and shuddered. 

They lay together, panting.

“Don’t leave me again,” John whispered.

“Never,” Sherlock said. “I found it unbelievably difficult to be without you.” 

John soaked that up for a moment, and then said gently, “Had to make your own tea, did you?” He felt Sherlock smile against his hair. 

John unwound himself from Sherlock with reluctance. He wasn’t ready, but it was probably time; this would not be a good thing to rush. He stood, then helped Sherlock to his feet. Sherlock scrubbed at his belly with his coat and then offered it to John. “This feels like sacrilege,” John said.

 “It’s just a coat,” Sherlock said, but John saw his fingers twitch across the fabric.

“We’ll get you another,” he said, and Sherlock looked almost as though he might smile. John padded over to the medical kit while Sherlock cycled the coat through the airlock. John laid out the supplies slowly.

“Possibly it was foolish to release a bunch of fluids before attempting major surgery,” John said. Sherlock made no reply, just looked at him solemnly. The computer beeped and John didn’t bother checking it. He knew well enough what it would tell him. 

“Here’s how this will go,” John said, trying to stay focused on the clinical details. “I’m going to administer a local and then—“ he paused only for a second “—remove the leg. The blade will cauterize as I go.”

John’s hands prepared the hypo-spray with a surety he didn’t feel. “You’ll need to jettison it. Watch that I don’t go into shock. I shouldn’t; no blood loss or pain right away. Then we’ll get rattled about a bit while landing and afterwards we’ll have a nice visit to the infirmary.”

John sat, wincing as his naked skin met the cold floor. He took a breath and then injected the anesthesia into his leg. It took mere moments for numbness to spread underneath his skin. He bit his lip as the last sensations his leg would feel slowly slipped away.

“You don’t have to watch,” John said. “I mean, you can if you think that it would be interesting—“

Sherlock made a pained noise. He’d wrapped his arms around his body and his eyes seemed too large in his face. “It’s not interesting to me,” he snapped. “It’s a travesty. Do you really think I’d appreciate the science of this?”

John took a breath, blew it out. “You find all sorts of things interesting,” he said mildly. “It’s only transport.”

“No,” Sherlock said emphatically. “Not for you.” He rubbed his hand over his eyes, and when he spoke again his voice came in a low murmur. “I faked my own death to protect you. Your well-being is vital to me.”

John swallowed. “I feel the same way, all right? That’s— that’s why it’s me about to do this.”

“I can’t watch,” Sherlock said, and moved to stand behind John. 

John knew that it was time, probably past time. He wished now that he’d taken something to blunt the edge of his nerves, but really it seemed more important to have steady hands. John looked down at his leg, saying farewell to its familiar contours, its rough and smooth places, the marks and scars of a body well-used. He picked up the laserknife.

Suddenly he felt the bite of an injection in his arm. He turned to see Sherlock putting the hypo-spray aside. Then Sherlock braced him by the shoulders.

“Sherlock, what are you—“ The room began to spin. “No, need to be awake, don’t—” 

“Shh,” Sherlock said. “Trust me.” 

John blinked slowly once, twice, and then slid into unconsciousness.

* * *

He awoke in hospital. Even on far-flung colony worlds the institutional feel of the decor was unmistakeable. He felt an IV in his arm and the beeps and clicks of the life-sign monitor told him that his body was working fine. He squeezed his eyes shut a moment. He felt a bit banged up, probably from the splashdown, but unexpectedly decent otherwise. He felt nothing from his leg, which was probably a good thing. He felt a bit nettled that Sherlock had taken John’s surgery into his own hands, but also a bit relieved. He took a deep breath, pulled back the sheet, and looked down.

Both legs stretched across the bed. There wasn’t a mark on him. John froze. Had Sherlock— had he— surely he must have— 

John frantically pushed the call button. The nurse had barely entered the room before John asked, “Where is Sherlock? The other man from my ship?” 

The nurse tightened her lips. Her face looked serious. John recognized it, having delivered bad news enough times himself. “I’ll fetch the Administrator,” the nurse replied, and left, closing the door firmly behind her.

“Oh, God,” John said.

That bloody mad bastard. He’d jettisoned himself to save John. John felt it come crashing over him, every feeling he’d had after Sherlock’s first death. He felt something rising in his throat, and he knew that if he let it out he would howl and scream and never stop. His heart pounded painfully in his chest and he couldn’t breathe; he felt as though his ribcage were collapsing in on itself. Sparks began to dance before his eyes and the last thing he heard was the urgent shriek of the monitors before everything went black.

* * * 

When John came to awareness the second time an officious-looking man in a lab coat stood at the end of his bed.

“Doctor Watson,” he said. “I’m sorry to disturb your recovery but we really do need for you to take charge of the quarantine. Can you get up?”

John never wanted to get up again. But Sherlock had paid the ultimate price to save the colony; John would do his part. He maneuvered himself out of bed. He pulled on clean clothes numbly, a constant drumbeat sounding: _Sherlock is dead. Sherlock is dead._ The image of Sherlock’s body floating in space, his blood boiled and his beautiful eyes frozen open, haunted him. 

He turned at a knock on the door. The nurse stood there, a bundle of paperwork in her hands.

“I’m Nurse Bell,” she said, “and I’m to help you with the quarantine since the other nurses have caught it. If you’ll come with me we can get started.”

John followed, feeling a telltale weakness in his leg. 

“I just heard that they’ve dropped the charges against your friend,” Nurse Bell said. “I thought you’d want to know.”

“Charges,” John said. “What does that matter now?”

She frowned at him. “It’s quite a thing to have hanging over you,” she said. “And he looks a bit soft to survive hard labor on Wayford; winters here are dreadful. But we’ll have you both out of here well before then, provided we get this virus under control.”

John blinked at her. “What — where is he?”

She pointed. “Across the courtyard. But he’s still unconscious, and —“

John walked away without waiting for her to finish speaking, his strides increasing in speed. He found Sherlock at the end of a long hall, in bed and connected to all the usual monitors and machines. John stood a moment, feeling as thought the world had suddenly snapped into focus, a rush of relief and elation bubbling through him. His body felt weightless, as though he might fly to Sherlock and dance through the skies with him. He crossed the distance to the bed and stroked his hand through Sherlock’s dark curls. 

“Cheated death again, I see,” he whispered. John leaned forward and breathed in the warm scent of Sherlock’s skin underneath the sharp antiseptic smell of the hospital. He pressed a kiss to Sherlock’s forehead. 

Then his face tightened, tension radiating up his neck and into his jaw. His eyes dropped to the outline of Sherlock’s body in the bed. He gently pulled the blankets back. Sherlock’s left leg rested against the sheets, alabaster and perfect. His right leg was gone.

John didn’t know he was crying until the tears began to fall, soaking into the sheets. He put his head down next to the truncation at Sherlock’s thigh, ran his fingers over the puckered, seared skin, and wept. 

After a while he wiped his eyes, brushed another kiss against Sherlock’s cheek, and went to work.

* * *  

John dozed by Sherlock’s bed, his visions of treating feverish and vomiting colonists true enough to life that he wasn’t sure if he dreamed or still worked. He felt a familiar set of long fingers encircle his wrist and shook himself muzzily awake. He took Sherlock’s fingers into his own and laid a soft kiss against them.

“Hey,” he said softly.

“John.” Sherlock croaked. John passed him a cup of water, not releasing his other hand. Sherlock’s gaze seemed loose and relaxed but alert. 

“Anything hurt?” John asked.

“No,” Sherlock replied.

John sat there a moment longer, his eyes drinking in Sherlock’s face, awake and alive. Then, “Why?”

Sherlock coughed, took another drink of water. “You insisted on denying me the right to pay the price for my own mistake. Besides, the colony needed you.”

“So you pretended you couldn’t bear to watch and then pulled a fast one.”

“I _couldn’t_ bear to watch. I said that it would have been a travesty and I meant it. And—“

“This is a bit like the last time you acted unilaterally to save me, you know,” John said. “I suppose I should be angry but I’m not.” He swallowed. “I don’t have words for how much this means to me.” He stroked his thumb across Sherlock’s hand. “I’ll help you through this. I’ll be there. Always.”

Sherlock grinned, a bit lopsided and loopy from the meds, and squeezed John’s fingers. “Yes,” he said. “You certainly can’t leave me now, can you? But John —”

Nurse Bell bustled through the door.

“Mr Holmes, the regeneration unit has come available. Are you ready to go?”

John felt his jaw drop.“You’re a regen candidate?” He stared at Sherlock, brows raised. “Why did you let me think you weren’t?”

Sherlock shrugged. “I didn’t know until recently; Mycroft let me believe otherwise. He thought it would make me more inclined to take risks if I knew.”

“Obviously he was right! Why—” John clenched his jaw. “I was a surgeon. Why didn’t you let me—“ he waved his hand in the general direction of Sherlock’s leg. 

Sherlock leaned forward, his expression serious. “You’d suffered enough.”

John shook his head. “I still can’t believe that you did this.” He took a slow breath, tried to calm the tummult of feelings inside his chest. “Regens aren’t perfect, you know. It won’t be exactly like your other leg.”

Sherlock tilted his head to the side, then looked up at John with a half-smile. “Well, then we’ll have a matching set, won’t we.”

John felt a giggle trying to escape from his throat.

“Besides,” Sherlock continued, his mouth creasing into a grin, “now I will win every argument for the rest of our lives.”

The giggle escaped and John laughed, a full-body laugh for the first time in two years. Sherlock laughed with him, their voices twining together. John kissed Sherlock’s fingers again. He bent to whisper in Sherlock’s ear. “Newly regenerated skin is super sensitive, you know.” He licked his lips, gratified to hear Sherlock’s indrawn breath. Then John let Nurse Bell bustle Sherlock away, full of the precious knowledge that their lives once again unspooled together, the two of them against all the worlds.

**Notes for the Chapter:**

> Credit for the premise, the maths and the physics for this story goes to Tom Godwin and Don Sakers. Godwin first, in the sci-fi classic [The Cold Equations](http://www.spacewesterns.com/articles/105/) and Sakers when he reworked the tale in [The Cold Solution](http://www.amazon.com/The-Cold-Solution-Don-Sakers-ebook/dp/B005JFLL3Q). I wanted to put John and Sherlock in a terrible situation and this story has always haunted me.


End file.
